1. Field of the Invention
The present invention relates to an electronic component housing unit that accommodates an electronic component within a case, and that is clamped around and secured to the intermediate portion of a length of an electric wire.
2. Description of the Related Art
A problem encountered with such housing units is that certain of a variety of sensors mounted on an automotive may intermittently receive, along an electric wire or wires, conduction noise produced by a device such as a horn or a wiper motor, which generates noise having a high frequency element, or external noise, generated by neon signs, or induction noise, and this noise can cause a device to operate erratically. Conventionally, a technique for the removal of noise has been proposed that involves the employment of an electronic component housing unit (a noise prevention device), as disclosed in patent document 1.
Patent Document 1: JP-A-2006-109587
An automotive installation problem, which can adversely affect the operation of an electronic component accommodated within a conventional electronic component housing unit, is that when the electronic component housing unit is mounted on a vehicle, concentrated stress is applied to, and can deform, the unit.
Specifically, an electronic component housing unit, which accommodates, in an incorporated case, an electronic component, is intended to be clamped around and secured to the intermediate portion of a length of electric wire. To complete mounting of such a housing unit on a vehicle, first, a resin fitting portion is inserted into a through hole and temporarily fixed to a metal, load bearing face on which the housing unit is to be mounted. Then, a screw is used to securely attach a grounding terminal lead to the metal, load bearing face. During this final mounting operation, when the screw is rotated to tighten the grounding terminal lead, the housing unit bearing the grounding terminal may also turned by a torque applied by an impact wrench. The resin fitting portion, however, is used to impede such movement. Therefore, the resin fitting portion is not only employed for temporal tacking but also for preventing rotation, and for this purpose is integrally formed with a cover that engages the case of the electronic component housing unit. However, if excessive driving force is applied while the screw is being tightened, this excessive force is also applied to the resin fitting portion that, in effect, connects the cover to the case. As a result, when the cumulative stress applied to such a relatively weak portion becomes too great, deformation can occur.
While taking the above described situations into account, one objective of the present invention is to provide an electronic component housing unit that can prevent deformation due to screw tightening torque.
In order to achieve this objective, according to a first aspect of the invention, provided is An electronic component housing unit comprising a case accommodating an electronic component and at least a part of an electric wire, a grounding terminal including a base portion provided so as to be engaged with the case, an earth portion continued from the based portion and to be attached to an external object on which the electronic component housing unit is to be mounted, and a fitting portion to be fitted to the external object, wherein the fitting portion is secured to the base portion.
According to this aspect of the invention, since the fitting portion is coupled with the grounding terminal, the fitting portion can absorb the rotation torque generated while a screw is being driven and impede the turning of the electronic component housing unit bearing the grounding terminal, without stress being transmitted, for example, to the case of the housing unit. As a result, the occurrence of deformation can be avoided. Furthermore, according to this invention, since the fitting portion is connected to the grounding terminal, the area of the load bearing surface employed as the mounting portion can be reduced.
According to a second aspect of the invention, for the electronic component housing unit of the first aspect, the base portion of the grounding terminal is formed so as to serve a cover for the electronic component accommodated in the case.
According to this aspect of the invention, the grounding terminal is made of metal, and the case wherein the electronic component is accommodated is covered by the base of the grounding terminal. Therefore, a structure is provided that is difficult to deform.
According to the first aspect of the invention, deformation due to screw tightening torque can be prevented, and the area of a load bearing surface required for a mounting portion can be reduced.
According to the second aspect of the invention, the rigidity of the electronic component housing unit can be increased to provide a structure that is resistant to deformation.